INFLUENCE OF THE CONCENTRATION OF ELECTRO- 

 LYTES ON SOME PHYSICAL PROPERTIES OF 

 COLLOIDS AND OF CRYSTALLOIDS. 



By JACQUES LOEB. 

 (From the Laboratories of The Rockefeller Institute for Medical Research.) 



(Received for publication, November 19, 1919.) 

 I. mXEODUCTION. 



When we separate neutral solutions of salts with monovalent cation 

 from pure water by a collodion membrane, water will diffuse into the 

 solution. The writer has shown in a preceding publication^ that the 

 initial rate of diffusion will at first increase with the concentration of 

 the electrolyte, but as soon as the concentration of the latter is about 

 m/256, the initial rate of diffusion of water into the solution will in the 

 case of many electrolytes diminish with a further increase in the con- 

 centration of the electrolyte until at a concentration varying between 

 m/32 and m/8 (according to the nature of the electrolyte) a minimum 

 is reached. This phenomenon is due to the influence of the ions on 

 the electrification and rate of diffusion of water through the collodion 

 membrane. In the presence of neutral solutions of salts with mono- 

 valent or bivalent cation, water diffuses through the collodion mem- 

 brane as if its particles were positively charged and as if they were 

 attracted by the anion and repelled by the cation of the electrolyte 

 with a force increasing with the valency of the ion. With low con- 

 centrations of electrolytes the attractive action of the anion upon the 

 positively charged particles of water prevails over the repulsive force 

 of the cation, while, when the concentration exceeds a certain value, 

 which for a number of salts is about m/256, the repelling force of the 

 cations of the electrolyte upon the positively charged particles of the 

 water increases more rapidly than the attractive force of the anions. 

 This idea is supported by the fact that the addition of salts with 



1 Loeb, J., /. Gen. Physiol., 1919-20, ii, 173. 



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